Flue insulation

rem284

Well-Known Member
I am think of insulating the flue of my wood burning stove because I sometimes get condensation in the flue. I all ways have good dry wood and run the stove at the recommended temp. The problem seems to be mostly when the stove isnt going or shut down over night. It will have to be of the back fill type. I have heard that if vermiculite gets wet or draws moisture from damp masonry it becomes a solid spongy mess and is difficult to remove if the liner needs replaced in the future. So the questions are

Is there a better back fill insulation that does not become a problem

Is there another way of avoiding the small amount of condensation
 
Ha Ha, its bad enough sitting almost naked in the house mid winter and being a slave to the stove.
 
The question is why are you getting condensation in the flue, that needs to be resolved first. My liner runs through my chimney with no back fill. You need to ensure there is a form of ventilation to the stack the ones I have seen have a 50mm plastic pipe inserted at the chimney which allows air flow in the chimney outside the liner. Many different opinions to fill or not to fill. If you do install a liner you must remember to get the chimney swept before you have it installed. There are a couple of stove suppliers/installers on here who may be a better source of information and advise.

D
 
The liner is in, I did clean the chimney before installing. The pot has three "horn" vents, so air can get in at the top but the bottom is sealed. Where is the 50mm plastic pipe inserted about. The condensation is coming down on the inside of the flue and seeping out the end cap on the T-piece. I am living in a wet part of Scotland
 
My thoughts are if chimney is not capped by anything rain cover etc then put a Chinese hat on it and fill with vermiculite as its the cavity between flue liner and existing chimney that is causing the condensation as its not filled. After its filled if you still get condensation I would then check where chimney exits the roof for water ingress or failed Harling on chimney etc.

Andrew
 
Are you sure its condensation not rain water ingress. I fitted my liner when we had to replace the roof and mine has a stainless steel bird proof cap which is attached to the pot. In some cases the 50mm pipe is next to the pot but goes into the void between the liner and the inside of the chimney thus allowing the chimney to breath. Sorry difficult to explain. Is your chimney excessively tall. May speak to my tame chimney sweep/log burner guru next week.

D
 
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